For example, Japanese Patent Application Laid-Open Publication No. 2013-519265 (Patent Document 1) describes a method for preventing repetitive refreshing of an address table which occurs at a neighbor node in the recovery from a fault in a ring network using a ring protocol specified by ITU-T G.8032. Specifically, in the recovery from a fault, a neighbor node usually receives a fault switch-back frame (NR, RB) from an owner node and deletes information of blocked port retained by both ring ports. According to the method of the Patent Document 1, however, the neighbor node does not delete the information of blocked port but updates it with information of the blocked port contained in the fault switch-back frame.